RDBMS

RDBMS is stand for Relational DataBase Management System. It's a Database Management System base on relational model invented by Edgar F. Codd.

The data in RDBMS is stores in database object call "table". Table is a collection of related data entries and it consist of numerous columns and rows.

A table is the most common and basic store object in RDBMS.

Every table is broken up into small piece call "field". A field is a column in a table that is designed to maintain specific information about every record in the table.

Database Normalization

Database normalization is a process of efficiently organizing data in database.

Purpose:

Remove redundant data.
Ensuring data dependencies make sense.

Steps to normalize data in database : using normal form:

1NF : remove duplicated data
2NF: devide into seperate table by primary key. If there is field indicated by a-part of primary key, make a new table from these field; then create a new table for relation between new table and existing table.
3NF : If there is a field indicated by another field and this field indicated by primary key, make new a new table from these fields.

*Note from writer:

When design database we always want to make an efficiently/best-fit-requirement/robust/consistence database. It's very confused if there is some field appear many times in several table or unknown fields. In this case, our database will be bigger than expected, hard to maintenance, very hard to extend, extremely hard to save performance, and in fact it will make more cost to company. Fortunately, using normal form(NF) can solve this problem.
With three steps : 1NF, 2NF, 3NF we can make clear relation database, no redundant data, and ensuring data consistence.

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